Generally, as a brake disc for a two-wheeled motor vehicle, there have been widely put to practical use a brake disc that is provided with an mounting portion to be mounted to a wheel and a sliding portion that makes sliding contact with a brake pad, and is formed by press-molding a single piece of metal plate, and a floating brake disc that is provided with an annular sliding disc having a sliding portion against which a brake pad is pressed, a hub disc which is attached to the inside of the sliding disc, and a plurality of connectors which connect the sliding disc and the hub disc to each other in a floating state.
Further, there has also been widely adopted a brake disc that includes a plurality of lightening holes formed on a sliding portion in a predetermined arrangement for the purpose of total weight reduction, improvement of the heat releasing property in the sliding portion, cleaning of a brake pad, and the like (see Patent Document 1, for example).
Furthermore, in order to prevent the generation of noise during braking, there have been developed a brake disc that includes two brake disc plates which are integrally laminated (see Patent Document 2, for example), and a brake disc that includes two brake disc plates one of which has an annular concave groove on the surface facing the other brake disc plate, wherein the brake disc plates are integrally laminated in such a manner that an damping member is arranged on the concave groove (see Patent Document 3, for example).